For the elimination of malodorous and harmful gaseous components, methods and apparatuses are known which comprise passing a gas containing malodorous and other components through a bed of granular or fibrous activated carbon. Such malodorous or harmful gases may contain sulfur-containing compounds such as hydrogen sulfide, mercaptans, sulfides, and nitrogen-containing compounds such as ammonia, amines, and aldehydes, carboxylic acids, hydrocarbons and carbon monoxide. These malodorous and harmful gaseous components are usually present in very low concentrations in the atmosphere but with the above-mentioned activated carbon alone, it is difficult to adsorb and remove all of these malodorous and harmful components. The rate and amount of elimination are also very meager. Therefore, a large quantity of activated carbon is required for the adsorption/removal of malodorous and harmful components. Furthermore, since the activated carbon bed presents a large flow resistance, it cannot smoothly remove the malodorous and harmful components, with the result that a fan is essentially required but this results in an increased electric utility cost. Replacement of deactivated carbon with a fresh one is also complicated.
For the adsorption/elimination of malodorous components which cannot be easily removed with activated carbon, the use of a chemical-supporting activated carbon honeycomb is proposed in Japanese Patent laid open No. 262742/1987. This honeycomb, when it is supporting an acid chemical such as sulfuric acid on activated carbon, is capable of removing ammonia, while it is able to remove hydrogen sulfide and the like when an alkaline chemical is supported.
However, even with this chemical-supporting activated carbon honeycomb, the malodorous and harmful components which can be adsorbed and removed are limited by the type of chemical supported. Therefore, it is difficult to adsorb and remove a variety of malodorous and harmful components with sufficient efficiency. Moreover, when an alkaline chemical is supported for elimination of sulfur-containing compounds such as hydrogen sulfide, the ignition point of the honeycomb is depressed. It is dangerous to use such an alkali-supporting activated carbon honeycomb in an ordinary inhabited area. In addition, since the activated carbon honeycomb is carbonaceous, it becomes readily inflammable, thus causing trouble in use. On the other hand, the addition of a flame retardant leads to a decrease in the amount of adsorption per unit specific surface area and, hence, a decrease in deodorizing efficiency. In these honeycombs, it is necessary to support a large amount of chemicals on the activated carbon honeycomb in order that an enough adsorption effect is achieved.
Japanese Patent Publication No. 9377/1987 discloses a deodorizer comprising an oxide and/or oxo acid of iodine supported on activated carbon. However, since this deodorizer is granular, the flow resistance in deodorization is too large for smooth treatment of gases. It is not easy to handle it, for example, changing a deactivated one for a fresh one.